Sound-reproducing apparatus



Jan. 7, 1930. T. LINDENBERG SOUND REPRODUCING APPARATUS Filed May 20, 1926 my .M e .a s MM- m wv K 6 7m k W, w ..3 v/v/ v um .41W

Patented Jan. 7, 1930 PATENT orifice g THEODORE LINDENBERG, F COLUMBUS, 'OHIO soUNn-itEPRoDUciNe APPARATUs Apiiiicatnm' filed may 2o,

-This invention relates to improvements in l sound reproducei-S, especially designed `for use in connection with i'adio receiving apparatus or other sound .5 trical sound developing and amplifying means. A

In the ordinary formsof loud speaker used in connection with radio apparatus, 1it is customary to employ but .a single diaphragm or other vibratory'member in the translation of the electrically created impulses into audible'sound Waves. DueV to the .physical limitations of the vibratory member, such as its sides, or the materials from which it is formed, it is considered imposT sible to obtain therefrom the volume, .overtones or true tonal sliadings which are pres entv in theoriginal rendition, and as a result the reproduced sound is'thought to possess a fiat, thin or hollow character lacking in n l y """'Fi`gure 3 is a vertical transverse sectional 4those essentials of roundness, volume-and bOdyby vwhich'pleasing and naturalrqualities in sound creation are determined.

Again, most ofthe present-reproducers or 2 from a single material which may respond Well and naturally to certain kindred orches-- tral instruments, notes or tones but do not respond With equal-or similar clarity to other instrumental sounds, particularly when the latter are created by instruments having no direct relationship with the materials employed in 'the reproducer. For example, a reproducer' involving wooden amplifying Walls is more likely to reproduce faithfully the music of a Niolin than will an amplifier having metallic Walls, althoughv the latter may be more advantageously used in the i 'eproduction of band music.

With these and other -conditions in mind. the present invention-has for a principal objectthereof to `teria'ls such as metal, Wood,

apparatus utilizing elec-A amplifiers have their vibratory Walls formed provide apparatus which' of and in itself is capable of reproducing faithfully and clearly practically all sounds peculiar individual prop- Y stretched diaphragm unitswhich, collectively' 1926. Serial No. 110,560.'

considered, are vformed f'rom different 'Inapaper or composition materials, and areadapted When si multaiic'ously vibrated by associated electroresponsive means to produce sounds of a natural .or musical quality, wherein the full range of audible sound Waves isreproducible together with a balance of proportionable reproduction of and created at the original sound source.

n the individual instruments and sounds present For a further understanding of the invention, reference is to be had to the following descrlption and the accompanying drawing, wherein:

. Figure l is a vertical longitudinal sectional view taken through the sound reproducing apparatus comprisingthe present invention,

Figure 2 is a horizontal sectional1vieW` vie\v\taken on the line 3-3 of Figure 1,

Figure 4 is an enlarged vvertical sectional vieu` taken through one lunits of the apparatus,

Figure 5 a' diagrammatic view of a circuit arra-ngement'.

In the particular' form of the invention herein selected for illustration and description`- although the invention is not limited to the specific form thereof, my improved sound reproducer is designated vin its entirety b vthe numeral l. v Possibly, the reprod ucer is formed to include a cabinet or casing which is formed to comprisea horizontal bottom wall 3, a vertical back Wall 4, anopenwfrout wall 5, end Walls '6 and a horizontal -top 7. The open front Wall may be provided uitha screen 8. constituting av sound' outlet and alsoto conceal internal structure.

Mounted Within the cabinet is a diaphragm base 9, having its ends only connected with the casing asl at l0. in order that said base may be employed. in the ci pacity of a sounding board. Secured to the base strip as 'at 9 are a plurality of vertically arranged sounding board sections 11, to the vertical edges -of which are connected a plurality of fins, taut membranes or diaof the diaphragm phragms 12.4V These diaphragme are preferably in the form of ribbons or strips, and have their upper andlower edges secured as at 13 in'any substantial or stationary man. ner to the corresponding edges of lthe sections 11. Asindicated in Figure 1 the diae phragms are formed from different materials, such as Wood,paper, metal or a molded composition material.`

, Tension is placed 0n the diaphragms and the latter are maintained in a partly stretched condition, by providing the sounding board sections 11 in this instance-With threadedl sleeves 14, in which are received set-'screws 15, the latter pressingupon bars f 16, arranged between the reari surfaces of' the diaphragms 12 'and the front surfaces, of the sections 11 at the points of connection `of said diaphragme with the sounding' boardsections.v -,l\/Ianifestly, by tightening fthe screws 15 the bars 16 are forced inanfoiitl Ward direction so as to place thediaphiagms,

' 25 l l @passing axiallythroughvalignedo 18 12 under the required degree ,opfhtensiop whereby .the same. Amay respond ',rnintitely'-jtoj the reeiprocatory. movement of tins-:17

"provided inthe base 9 and thesoun/ding lboard sections 11, the outer ends olthe'stylus of each unit is connected with the respective ,diaphragm vof that unit and the inner or `rear end of thestylus is connected With an j armature 19 situated inthe magnetic field of the coils 20. These coils are arranged in circuit with a sourceof electric signal oscillations obtained, for example, from radio receiving apparatus or other apparatus using electrical -means in the development of rality of reproducin a cabi-- lmounted within said cabinet, vibratory' sounding boards mounted Within said cabi-Iv net andfupon which said reproducing umts-1 y are mounted, each of said units consisting o a diaphragm, the diaphragm of said units` being formed from different materials, means for maintaining the said diaphragm under tension, and means for vibrating each of said diaphragins.

Intestimony whereof I aiiix my signature.

' THEODORE LINDENBERG sound. By the switch 21 shown in Figure 5 the coils 20 may be placedeither in series or in parallel relation with respect toeach other. and I have found that by varying the electrical potential of the coils a material and noticeable difference is obtainable in the '2 iinally reproduced sound.

The construction set forth provides a plu- I' .rality of diaphragm units each having indi'- vidual or characteristic sound creating prop-V erties which, if operated separately, would not produce a clear and accurate reproduction of a complete sound but when the com bmation of units is employed lllflithe units are simultaneously operated,l affini-ligand complete reproduction is secured'of'greatnaturalness and devoid of those mechanical properties so universally .present in reproduced music.

What is claimed is: v .12A sound reproducing apparatus comprising a plurality of reproducing units, each of said unitsincluding a' diaphragm vformed .trom a material possessing different resonating properties v than those of the other of `said reproducing units. 2. A sound reproducerfor radio receiving apparatus comprising a cabinet, a plu- 

